Linda Kvarnström has a BA/Sc in conservation at Gothenburg University and is an associate member of the CVMA/Corpus Vitrearum International Committee for Stained Glass Conservation.
She has previously worked at the York Glaziers Trust and is currently Head of Conservation at Uppsala Cathedral Stained Glass Studio, Swedenís only conservation studio for stained glass,
which she was involved in starting. The studio cares mainly for Uppsala Cathedralís stained glass, but also takes on outside commissions.

Erika Andersson gained a BA/Sc in conservation from Gothenburg University in 2012 and joined Uppsala Cathedral Stained Glass Studio in 2014. She has previously worked in archaeological
conservation at the Swedish National Heritage Board, where she has also done light ageing analysis of discolored stained glass containing manganese.

Retouching the past
Linda Kvarnström* & Erika Andersson

Uppsala Cathedral Stained Glass Studio

The lost paint of a stained glass window; how should we treat it? Should we leave it or should we try to reinstate what was once there? The answer is never simple. This paper
will illustrate the approach that was adopted during the conservation of the Sonís Window in Uppsala Cathedral.

The window was manufactured in 1892, but only 30 years later the deterioration of the vitreous paint had gone so far the parish was complaining. During the 1970ís restoration of
the cathedral, the majority of the windows were repainted, re-fired and some were replaced. Luckily the paint on the Sonís Window had fared better than most and was left without
too much interference.

By 2012, when the Sonís Window was next considered for conservation, the past had made its mark on the surface decoration in three different ways; loss of original paint, stop-gaps
of clear glass decorated with cold paint, and two panels that had been repainted and re-fired only six years earlier. How the stop-gaps and loss of painted detail should be approached
had by no means a clear answer, as this was the first time a stained glass window was to be conserved in Sweden following publication of international guidelines for conservation.

The cold paint was no longer attached to the stop-gaps. Whether they should be kept was discussed at length. In the end it was agreed to replace them with new repainted pieces,
as the light that was shining through the clear glass was severely distracting the eye from the painted detail in the surrounding areas.

Retouching areas with paint loss is a controversial topic in Sweden. A seminar was arranged which brought together the parish, art historians, authorities, stained glass conservators
and experts in other fields of conservation. Close examination of the glass surface revealed ghost lines of lost tracing paint, meaning that they could be retouched without any guesswork.
Could the retouching be reversible? Yes and no. The method of retouching on backing plates is, in theory, highly reversible. But once done, the church visitors and the parish would
likely complain if it was to be undone.

It was concluded that the tracing lines in the most important areas; faces, hands and inscriptions, should be retouched on backing plates - as long as a balance was kept with the
surrounding glass that was not retouched. All retouching and repainting of stop-gaps was discussed with and approved by a working group of conservators, an art historian and a heritage
consultant.